Retrofit 2.0 throwing "IllegalArgumentException: @Field parameters can only be used with form encoding". How to do right API query and fix it?

My problem is that I don't know how to start using Retrofit 2.0 with received API - mentioned below...

Firstly, I need to username, password, fbID (optional), gmailID (optional), twitID (optional), gender, birthDate, location (not required - if long and lat has values), longitude (optional), latitude (optional), profileImage (optional).

When all parameters are good - receive status = true. If not - receive status = false and required parameters which are wrong (e.g. mail is already taken)

So I can receive status = true or status = false and array with max 5 parameters (username, email, password, gender, birthDate).

I tried this API Interface:

public interface AuthRegisterUserApi {
    @PUT()
    Call<AuthRegisterUserModel> getStatus(
            @Field("username") String username,
            @Field("email") String email,
            @Field("password") String password,
            @Field("fbID") String fbID,
            @Field("gmailID") String gmailID,
            @Field("twitID") String twitID,
            @Field("gender") String gender,
            @Field("birthDate") String birthDate,
            @Field("location") String location,
            @Field("longitude") String longitude,
            @Field("latitude") String latitude,
            @Field("profileImage") String profileImage
            );

    class Factory {
        private static AuthRegisterUserApi service;

        public static AuthRegisterUserApi getInstance() {
            Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(ApiConstants.REGISTER_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();

            service = retrofit.create(AuthRegisterUserApi.class);

            return service;
        }
    }
}

with this API models (Pastebin.com)

and this code in Activity:

AuthRegisterUserApi.Factory.getInstance()
        .getStatus(
                usernameEditText.getText().toString(),
                emailEditText.getText().toString(),
                passwordEditText.getText().toString(),
                "", "", "",
                (maleRadioButton.isChecked() ? "male" : "female"),
                mYear + "-" + mMonth+1 + "-" + mDay,
                (geoLocationToggleButton.isChecked() ? geoLocationEditText.getText().toString() : ""),
                (!geoLocationToggleButton.isChecked() ? "50" : ""),
                (!geoLocationToggleButton.isChecked() ? "50" : ""),
                "")
        .enqueue(new Callback<AuthRegisterUserModel>() {
    @Override
    public void onResponse(Call<AuthRegisterUserModel> call, Response<AuthRegisterUserModel> response) {
        if(response.isSuccessful()) {
            if (response.body().isStatus()) {
                showToast(getApplicationContext(), "Registration ok.");
            } else {
                response.body().getInfo().getUsername();
            }
        }
    }

    @Override
    public void onFailure(Call<AuthRegisterUserModel> call, Throwable t) {

    }
});

I have error: java.lang.IllegalArgumentException: @Field parameters can only be used with form encoding. (parameter #1) for method AuthRegisterUserApi.getStatus

I tried to register user using Postman and it works when I used option Body -> x-www-form-urlencoded.

How can I create I register query to this API? Change @Field to something else? I have got this error always...

EDIT: Need to change API Interface to this:

public interface AuthRegisterUserApi {
    @FormUrlEncoded
    @PUT("/api/register")
    Call<AuthRegisterUserModel> getStatus(
            @Field("username") String username,
            @Field("email") String email,
            @Field("password") String password,
            @Field("fbID") String fbID,
            @Field("gmailID") String gmailID,
            @Field("twitID") String twitID,
            @Field("gender") String gender,
            @Field("birthDate") String birthDate,
            @Field("location") String location,
            @Field("longitude") String longitude,
            @Field("latitude") String latitude,
            @Field("profileImage") String profileImage
            );

    class Factory {
        private static AuthRegisterUserApi service;

        public static AuthRegisterUserApi getInstance() {
            Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(ApiConstants.BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();

            service = retrofit.create(AuthRegisterUserApi.class);

            return service;
        }
    }
}

BASE_URL = http://ip_address:8400 for me...

But still got error: Response.rawResponse = Response{protocol=http/1.1, code=400, message=Bad Request, url=http://ip_address:8400/api/register}. Using Postman with the same data I received code=201 Created. Don't know why...

you just missed @FormUrlEncoded above your Rest method call.

Your request is not encoded right, but are postman, so do change that :

@FormUrlEncoded
@PUT("/api/register")
    Call<AuthRegisterUserModel> getStatus(
            @Field("username") String username,
            @Field("email") String email,
            @Field("password") String password,
            @Field("fbID") String fbID,
            @Field("gmailID") String gmailID,
            @Field("twitID") String twitID,
            @Field("gender") String gender,
            @Field("birthDate") String birthDate,
            @Field("location") String location,
            @Field("longitude") String longitude,
            @Field("latitude") String latitude,
            @Field("profileImage") String profileImage);

Tell me if it's ok.

The problem was because I try to PUT e.g. longitude \ latitude \ location with no value - empty String.

I mean - there was a problem on API side. So to avoid that I changed method to this:

@FormUrlEncoded
@PUT(ApiConstants.REGISTER_URL_PART)
Call<RegisterModel> registerUser(
        @Field("username") String username,
        @Field("email") String email,
        @Field("password") String password,
        @Field("fbID") String fbID,
        @Field("gmailID") String gmailID,
        @Field("twitID") String twitID,
        @Field("gender") String gender,
        @Field("birthDate") String birthDate,
        @Nullable @Field("location") String location,
        @Nullable @Field("longitude") String longitude,
        @Nullable @Field("latitude") String latitude,
        @Field("profileImage") String profileImage
);

Now, when I go no value for one of them, I simply don't enclose this field.

I got a similar error message and I noticed that in my interface definition I missed the @ForUrlEncoded annotation - on top of the rest call that will use the form part, which seems to be the same thing you did at the first posted code block. Take a look at it.

Hope this helps.